“As the mayor of the most international city on Earth – where virtually all the world’s languages are spoken on our streets – I work constantly to improve my command of Cantonese, and of Mandarin, too. But now, I will deliver the rest of this morning’s remarks in another language that I also keep struggling to master: English.

“It’s an honor to be selected to chair the C40 Climate Leadership Group for the next two years. And it’s a privilege to ask all of you to join me now in applauding David for his exceptional leadership of C40 during these past two pivotal years.

“It was evident at last December’s UN conference in Copenhagen, where David made a passionate case for giving the world’s cities a greater role in combating global climate change. And in his own beautiful home city, the work he has done to begin dramatically shrinking Toronto’s carbon footprint demonstrates ‘leadership by example’ at its very best, and may be his greatest legacy to the city he has served so well.

“I also want to extend my thanks to our hosts, Chief Secretary Tang and the government and people of the special administrative region of Hong Kong. Dòjeh!

“We are enormously grateful for your hospitality. We also salute the steps that you are taking to make what has for centuries been one of the world’s preeminent centers of commerce a center of environmental action in the century to come.

“I also want to say how much I look forward to working with Sao Paulo Mayor Gilberto Kassab and his team in preparing our next C40 mayors’ summit in his marvelous city next May.

“My colleagues: it was just five short years ago that 18 of the world’s great cities came together, to share best practices and make common cause in the greatest global challenge of our time – reducing the greenhouse gas emissions that contribute so heavily to climate change.

“We recognized that cities – where for the first time in history, half the world’s people now live and which together account for more than 70 percent of the world’s greenhouse gas production – hold the future of humanity in our hands.

“It is in the power of all of us sitting in this room to fill that future with promise, not peril. We recognize that the tasks before us are not simple ones. We’ve seen how national governments have struggled, both at home and on the international stage, to take climate change actions.

“Cities must learn from that experience. We must be bolder. We must be more collaborative. And we must be more determined. Together, we must fill the vacuum of leadership ourselves.

“It’s true that filling this vacuum puts heavy burdens of responsibilities on us. But my colleagues, we must shoulder them. We must, not only because some of the greatest hazards of climate change – such as rising sea levels and increasingly extreme and destructive weather patterns – threaten our cities most directly.

“And we must, not only because the positive steps that we take, here and now, can bless the people we serve with greater health and prosperity, but we also must act now, because failing to would shift even heavier burdens onto the backs of our children, and their children, too. As stewards of our cities, this is not a legacy we are willing to accept. And that is why this organization must continue to grow even stronger, even more active, and even more ambitious.

“From its original nucleus of 18 cities, the C40 group has expanded to now include 40 members and 19 affiliate cities. Its partnership with the Clinton Climate Initiative, and with former President Clinton, has built it into a great organization – one befitting our role in the world.

“Because together, the cities we represent account for approximately 21 percent of the global Gross Domestic Product. Roughly 12 percent of the world’s carbon emissions are produced in our metropolitan areas. And nearly one of every 12 people on Earth lives in or near our cities’ limits.

“Our profile is so high and impact so great that the actions we take often produce positive ripple effects around the globe. London, for example, instituted congestion pricing as a way to reduce auto emissions and support mass transit – and today at least nine other C40 cities have followed suit, or are now prepared to.

“Bogotá’s extensive ‘bus rapid transit’ system now moves more than one million people through the streets of that city each day – and other cities, including my own, are following Bogotá’s lead. Our host city of Hong Kong, like Sao Paulo and other municipalities across the globe, is replacing fossil fuels with organic waste as a way to generate electricity.

“And I’m proud to say that under our administration, New York has enacted a set of green building laws that mandate the most ambitious effort that any city in the United States has yet taken to make existing buildings more energy-efficient. Implementing these laws will save New Yorkers $700 million a year in energy costs, greatly enhance our economic competitiveness, create more that 17,000 much-needed new jobs and shrink our carbon footprint by a size equivalent to that of an entire city of roughly half a million people.

“These measures are key elements in our comprehensive PlaNYC program to reduce greenhouse gas output in New York City by 30 percent by the year 2030 – an agenda that we unveiled on Earth Day in 2007, and that we will present in updated form at the Sao Paulo summit next May.

“Over the past five years, our cities have, in short, demonstrated that we are prepared to boldly confront climate change. As mayors, we know that we don’t have the luxury of simply talking about change without delivering it. As Mayor Miller put it in Copenhagen: ‘Nations talk; cities act.’

“And that is why, even as we ceaselessly continue to urge national and international action to address this mounting global crisis, we also must, and will, redouble our own efforts to make a sustainable world a reality. Achieving sustainability – that is the goal on which all our efforts will focus over the next two years. To move toward it, we will employ four key strategies – strategies that we have devised in consultation and collaboration with you. I will briefly outline them now.

“First, even as we continue to advance initiatives that Mayor Miller and his predecessors have launched, we will also broaden the C40 agenda. We will, of course, continue to focus on such longstanding priorities as those addressed in yesterday’s roundtable discussions: encouraging energy-efficient building retrofits; and promoting the use of electric-powered vehicles.

“The reasons are compelling. Consider this: in just 19 key C40 cities, there are more than 20 million vehicles. Converting even one percent of them to electric power would pay enormous environmental, and economic, dividends. Because make no mistake, the days of the oil-fueled auto are numbered – and cities that lead the transition to new alternatives will become more attractive places for economic investment.

“But there are also many other ways to make our cities sustainable: in water conservation, in waste recycling, and in greening our cities’ streets and public spaces, many of us are already at the forefront of action. And C40 will now join you in advancing these initiatives. Doing that will require even greater sharing of our ideas and experiences – which leads to our second strategy: encouraging C40 cities to cooperate more directly and closely with one another.

“We recognize that our cities have differences in climate, in geography, in population density, and in the legal, economic, and cultural frameworks in which we work. So our responses to climate change must be as well-tailored to those realities as a Hong Kong suit. But as major cities, we also face many similar challenges. So even as we acknowledge our differences, wherever possible we can and must also work directly with one another, because doing that can powerfully magnify our impact.

“For example: twenty-five C40 members have regulatory influence over taxi fleets that, combined, have more than one million vehicles. Think of that – a million-plus autos, the most iconic vehicles in our downtowns, that we can work together to make more efficient and less polluting, by sharing approaches to rules and incentives, by perhaps standardizing their design or performance benchmarks and maybe someday even by coordinating their purchase.

“By working together we can enlarge the scale of our success. And in line with that, I am honored that the Joint US-China Cooperative on Clean Energy has just translated New York’s PlaNYC into Chinese. I can’t wait to read it on the flight back to New York.

“But in all seriousness, I hope that the cities of China can benefit from this translation – just as I expect policymakers in New York City to study, and learn from, successes in China, and in the rest of the world. What we learn from such greater collaboration will also inform our third strategy: making the C40 Climate Group nothing less than the most authoritative source of information and analysis on all the climate change actions taking place in all the world’s great cities.

“I learned early in my career that if you can’t measure it, you can’t manage it. That’s true in business, and in government too. Only by regularly and rigorously measuring and analyzing our efforts can we learn what works, what doesn’t, and why, and then take more effective action. So over the next two years, we will concentrate on producing precisely such data and analysis.

“We will, for example, provide comparative analysis of cities with similar characteristics, so that we can learn from one another. We’ll identify where policies and practices successful in one city can be most readily replicated in others. That will help us cooperate with one another, collaborate with non-governmental organizations and philanthropies and more effectively work with our national governments.

“We’ll also make a concerted effort to let the world know what C40 and its member cities are doing. And this systematic effort will communicate a very important message to the rest of the world – that even as other levels of government may falter in meeting their climate responsibilities, or may sidestep them altogether, the world’s cities are pragmatically rising to the challenge.

“This will raise our visibility, and credibility, on the world stage. It will help us fill the void of global leadership, and attract the assistance, including the financing, that our cities so desperately need to meet our goals.

“But nothing will enhance our visibility and credibility more than our fourth and final strategy for the next two years: setting high standards, and holding ourselves accountable to meeting them.

“By joining C40, each of our cities has made a commitment to action – a commitment that must be matched by an equal willingness to be judged on our progress, and be 100 percent accountable. So let’s publicly identify all the initiatives that we’re undertaking. Let’s engage with each other in advancing them. Let’s set clear, quantifiable benchmarks for implementing them. And let’s regularly and openly assess our experience with them.

“Not everything we do over the next two years is going to be a success. In fact, if all our efforts ended in triumph, it would suggest that we’re not setting our sights high enough. And we will be as open and honest when we miss our targets as when we hit them dead-on. Because such candid reporting establishes an invaluable baseline of information for future actions by our cities, and other cities around the world. And it will do something more.

“Our transparency will give people everywhere confidence that cities – the level of government closest to the majority of people on earth – have the foresight and the courage to confront the greatest challenge that humanity has ever created for itself.

“My colleagues, the best scientific data tells us that it is long past time to address that challenge. And the best demographic data tells us that cities must lead the way. Because as the world’s population grows, the global pace of urbanization continues to accelerate.

“Just consider these facts: a century ago, only one in ten of the world’s people were city dwellers. Today it’s estimated that by the year 2050, almost three-quarters of the people of the world will make their homes in cities.

“A generation ago, China’s urban population was roughly 170 million people. Today it is more than three times that. And as recently as 1950, only one of the world’s metropolitan areas – that of my own New York City – had a population greater than 10 million people. Today, there are 17 such ‘mega-cities’ – 11 of them here in Asia.

“This rapid urbanization has produced difficult, and often dire, challenges in housing, sanitation, and public health. And the intense burning of fossil fuels in the world’s cities not only contributes to climate change; it also clogs their streets, pollutes their air, and shortens the lives of their millions of residents.

“But history tells us that cities also create the resources and unleash the technology that can solve those very problems, and lead to greater prosperity. There is, in fact, a virtuous, self-reinforcing cycle linking urbanization, prosperity, and sustainability.

“We can see that today, in cities that have already started to become more energy-efficient and less polluting. The residents of such low-carbon cities enjoy longer, healthier lives. And the steps that we take to reduce reliance on fossil fuels – by power plants, by autos, and also in heating and cooking in individual homes – will substantially improve the quality of the air in our cities’ most densely populated and often poorest districts.

“Some will tell us that we can’t afford to sacrifice growth to protect our environment. But that argument ignores the for-too-long unaccounted and devastating economic, environmental, and human costs of a wasteful fossil fuel dependence.

“It also overlooks the economic opportunities that the development of green technology will create. So in fact, going green is the only path to long-term prosperity that we have.

“In the arts and sciences, in culture and commerce, cities around the world have for centuries fired human imaginations and unlocked human creativity. The restless, enterprising spirit fostered in the world’s cities launched the process that today knits us all into one global community.

“It also holds out the promise of our finding common solutions to the challenges posed by climate change. Now, by meeting the challenges posed by climate change, the cities of the world, led by the C40 group, can ensure that our global community will not only survive; it will flourish. That must be our goal.

“And I am honored by this opportunity to work with you all in helping make it a reality during the next two years. Thank you all very much.”